JP2000173802A - Structure of chip resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely use self alignment due to surface tension of fused solder by mounting a chip resistor on the upper surface of a printed board or the like, in such a manner that both auxiliary electrodes of the chip resistor abuts against both electrode pads, and fusing solder paste. SOLUTION: In this chip resistor, one end portions 12a, 13a of a cover coat 7 side in both auxiliary electrodes 12, 13 are so stacked on the upper surface of the cover coat 7 that the one end portions 12a, 13a of both auxiliary electrodes 12, 13 protrude from the surface of the cover coat 7, or both end portions 7a, 7b of the cover coat 7 are so stacked toward the lower sides of both auxiliary electrodes 12, 13 that the one end portions 12a, 13a of the cover coat 7 side in both auxiliary electrodes 12, 13 protrude from the upper surface of the cover coat 7. Thereby the protruding end portions 12a, 13a abut against a printed board 16 in advance of the upper surface of the cover coat 7 in both auxiliary electrodes 12, 13 and it can be surely avoid that the cover coat 7 comes into contact with the printed board 16 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip formed by forming at least one resistive film, terminal electrodes at both ends thereof, and a cover coat covering the resistive film on the surface of an insulating substrate formed in a chip type. It relates to the structure of a type resistor.

[0002]

2. Description of the Related Art A conventional chip-type resistor has a cover coat for covering a resistive film formed on the surface of a chip-type insulating substrate, as described in, for example, JP-A-60-27104. This chip type resistor was printed because it was considerably protruded from the surface of the terminal electrode with respect to both ends of the resistive film and the step between the surface of the cover coat and the surface of both terminal electrodes was considerably large. When soldering to a printed circuit board with the resistive film side of the chip-type resistor facing the printed circuit board, one side often floats from the printed circuit board, making it impossible to solder reliably. Was to do.

Therefore, Japanese Patent Application Laid-Open No. 4-10 is a prior art.
No. 2302 discloses that an auxiliary electrode is formed on the surface of both terminal electrodes with respect to both ends of a resistive film, thereby eliminating or reducing a step between the auxiliary electrode and the cover coat. It is proposed to prevent the floating of

[0004]

However, in the prior art, the surface of the auxiliary electrode formed for both terminal electrodes is configured not to exceed the surface of the cover coat. When the chip-type resistor is placed on a printed circuit board or the like with the resistive film side of the chip-type resistor facing the printed circuit board, the surface of the cover coat is placed on the printed circuit board or the like. Because of the contact, when soldering in that state, it is possible to automatically position the chip resistor at a predetermined soldering location for the chip resistor by using the surface tension of the molten solder. In other words, self-alignment due to the surface tension of the molten solder can be used to correctly position the chip-type resistor at the soldering location and solder it. It was there is not a problem that can be.

SUMMARY OF THE INVENTION An object of the present invention is to provide a chip-type resistor which solves this problem and can reliably utilize self-alignment due to the surface tension of molten solder during soldering.

[0006]

In order to achieve this technical object, the present invention provides a chip type insulating substrate having a resistive film, a terminal electrode at both ends thereof, and a cover coat covering the resistive film. Forming, further, in a chip-type resistor formed by forming an auxiliary electrode on the surface of both terminal electrodes,
One end of the cover coat side of the two auxiliary electrodes,
On the surface of the cover coat, one end of the two auxiliary electrodes are overlapped so as to protrude from the surface of the cover coat, or
Both ends of the cover coat are superimposed on the lower side of the auxiliary electrodes such that one end on the cover coat side of the auxiliary electrodes protrudes from the surface of the cover coat. ".

[0007]

Operation and effect of the present invention
One end of both auxiliary electrodes formed with respect to both terminal electrodes will protrude from the surface of the cover coat, so that the chip resistor is connected to the printed circuit board or the like with respect to the resistive film side of the chip resistor. When facing the printed circuit board and placing it on the printed circuit board,
Of the two auxiliary electrodes, one end protruding from the surface of the cover coat comes into contact first, and it can be reliably prevented that the cover coat comes into contact with the printed circuit board side, in other words, the cover coat is lifted from the printed circuit board or the like. State.

Therefore, a solder paste is applied to the upper surface of the electrode pad on the upper surface of the printed circuit board or the like, and then the chip resistor is mounted on the upper surface of the printed circuit board or the like, and both auxiliary electrodes of the chip resistor are mounted on the upper surface. By melting the solder paste after being placed so as to be in contact with both electrode pads, the chip-type resistor is self-aligned with respect to both electrode pads on a printed circuit board or the like by the surface tension of the molten solder. After being automatically shifted to the correct soldering position, the soldering is performed at the correct position.

Therefore, according to the present invention, when a chip type resistor is soldered downward to a printed circuit board or the like, the chip resistor is automatically and correctly positioned at a predetermined soldering position by self-alignment due to the surface tension of the molten solder. Since the positioning can be performed, there is an effect that the number of steps required for mounting on a printed board or the like can be greatly reduced. In particular,
As described in claim 2, by adopting a configuration in which the width of the portion of the cover coat where the two auxiliary electrodes overlap is made smaller than the width of the portion where the two auxiliary electrodes do not overlap, the details will be described later. Thus, there is an advantage that the certainty of recognizing the chip-type resistor by the camera can be improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In this figure,
Reference numeral 1 denotes a chip-type insulating substrate. On the upper surface of the insulating substrate 1, a pair of left and right upper surface side terminal electrodes 2, 3 are provided.
And a resistance film 4 connected therebetween. Further, on the upper surface of the insulating substrate 1, an undercoat 5 made of glass covering the resistance film 4 and a middle coat 6 made of glass or the like covering the undercoat 5 are formed. And a cover coat 7 of black glass that covers the entire middle coat 6.

On the lower surface of the insulating substrate 1, a pair of left and right lower surface electrodes 8 and 9 are provided, and on both left and right end surfaces of the insulating substrate 1, the upper surface terminal electrodes 2 and 9 of the insulating substrate 1 are provided. Side electrodes 10 and 11 for electrically connecting the lower electrode 3 and the lower electrodes 8 and 9 are formed. Auxiliary electrodes 12 and 13 are formed on the upper surface of the insulating substrate 1 to cover the upper electrode terminals 2 and 3, respectively. That is, the auxiliary electrodes 12 and 13, the upper surface side terminal electrodes 2 and 3, the lower surface electrodes 8 and 9, and the both side electrodes 1
On the surfaces of 0 and 11, metal plating layers 14 and 15 composed of, for example, a nickel plating layer as a base and a solder plating layer or a tin plating layer are formed.

When forming the cover coat 7 and the auxiliary electrodes 12 and 13, one end 12 of the auxiliary electrodes 12 and 13 on the cover coat 7 side is used.
a, 13a are provided on the upper surface of the cover coat 7, and one end portions 12a, 13a of the auxiliary electrodes 12, 13 are provided on the upper surface of the cover coat 7.
Or both ends 7a and 7b of the cover coat 7 may be overlapped so as to protrude from the surface of the
One end portions 12a and 13a of the two auxiliary electrodes 12 and 13 on the cover coat 7 side are overlapped so as to protrude from the upper surface of the cover coat 7 toward the lower side.

With this configuration, the one end portions 12a and 13a of the auxiliary electrodes 12 and 13 project from the upper surface of the cover coat 7, so that the chip type resistor can be used as shown in FIG. , The printed circuit board 16 is connected to the resistive film 4 side of the chip type resistor by the printed circuit board 1.
6, when placed on the printed circuit board 16, one end portions 12 a, 1 of the auxiliary electrodes 12, 13 projecting from the upper surface of the cover coat 7.
3a contacts first, and the cover coat 7
Contact with the side can be reliably avoided.

Therefore, a solder paste is applied to the upper surfaces of the two electrode pads 16a and 16b on the upper surface of the printed circuit board 16, and then the chip type resistor is mounted on the upper surface of the printed circuit board 16, By mounting the auxiliary electrodes 12 and 13 so as to be in contact with the electrode pads 16a and 16b and then heating and melting the solder paste, the chip-type resistor allows the electrode pads 16a and 16b to contact the electrode pads 16a and 16b. Then, the solder is automatically shifted to the correct soldering position by self-alignment due to the surface tension of the molten solder, and then soldering is performed at the correct position.

The chip-type resistor having the above-mentioned structure is manufactured in the following general order. That is, as shown in FIG. 4, a pair of left and right upper surface side terminal electrodes 2, 9 are formed on the upper surface of the insulating substrate 1 in which a pair of left and right lower surface side electrodes 8, 9 are previously formed on the lower surface.
3 and the resistive film 4 are formed (when these upper surface side terminal electrodes 2 and 3 and the resistive film 4 are formed, the upper surface side terminal electrodes 2 and 3 are formed first, and then the resistive film 4 is formed. Alternatively, the resistive film 4 may be formed first, and then the upper surface side terminal electrodes 2 and 3 may be formed.

Next, as shown in FIG.
Is formed on the undercoat 5 and the resistive film 4 by irradiating a laser beam or the like so that the resistance value of the resistive film 4 becomes a predetermined value. After the trimming adjustment is completed, a middle coat 6 that covers the undercoat 5 is formed, and the trimming groove 17 is sealed with the middle coat 6.

Next, as shown in FIG. 6, a cover coat 7 made of black glass is formed so as to cover the middle coat 6, the undercoat 5 and the resistive film 4, and then, as shown in FIG. 12 and 13 are formed. After forming both side electrodes 10 and 11 on the insulating substrate 1, the whole is subjected to barrel plating to thereby form the auxiliary electrodes 12 and 13, the upper surface side terminal electrodes 2 and 3, and the Lower surface side electrodes 8, 9 and both side surface electrodes 1
Metal plating layers 14 and 15 are formed on the surfaces of 0 and 11
The chip resistor shown in FIGS. 1 and 2 is used.

The cover coat 7 and the auxiliary electrodes 12 and 13 are formed by screen printing, so that the cover coat 7 and the auxiliary electrodes 1 and 13 are formed by screen printing.
While there is a relative printing misalignment between the chip resistors 2 and 13, when automatically mounting the chip resistor on a printed circuit board or the like, the shape of the black cover coat 7 of the chip resistor is used. Is recognized by the camera.

In this case, if the overall shape of the cover coat 7 is a rectangular shape having the same width over its entire length as shown in FIG. 12 and 13 are horizontal dimension E
In this case, as shown in FIG. 11, a part of the cover coat 7 protrudes from both or one of the side surfaces of both the auxiliary electrodes 12 and 13, so that the black color of the chip-type resistor in plan view. Since the cover coat 7 has a shape in which the protruding portion is added to the rectangle and does not have a complete rectangular shape, recognition errors frequently occur in recognition by the camera.

On the other hand, according to the present invention, as shown in FIGS. 6 and 7, the width of the cover coat 7 is reduced at a portion where the auxiliary electrodes 12 and 13 overlap each other, as shown in FIGS. As described above, the four corners of the rectangle were cut off obliquely. By forming in this manner, when the auxiliary electrodes 12 and 13 are shifted from the cover coat 7 by the dimension E in the horizontal direction as shown in FIG. Since it is possible to prevent the auxiliary electrodes 12 and 13 from protruding from both or one of the side surfaces, the black cover coat 7 can be maintained in a substantially perfect rectangle in a plan view of the chip type resistor. The occurrence of mistakes can be reliably reduced.

The narrowing of the width dimension of the cover coat 7 at the portion where the two auxiliary electrodes 12 and 13 overlap is achieved by forming the cover coat 7 into a shape in which four corners of a rectangle are cut off obliquely. The present invention is not limited to this. As shown in FIG. 9, four corners of a rectangle may be cut out at right angles.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of a chip resistor according to an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a vertical sectional front view showing a state where the chip resistor is soldered to a printed circuit board.

FIG. 4 is a plan view showing a state in which a resistive film and both terminal electrodes are formed in the chip-type resistor.

FIG. 5 is a plan view showing a state where an undercoat is formed on the chip-type resistor.

FIG. 6 is a plan view showing a state where a cover coat is formed on the chip-type resistor.

FIG. 7 is a plan view showing a state where both auxiliary electrodes are formed in the chip-type resistor.

FIG. 8 is a plan view showing a printing shift between a cover coat and both auxiliary electrodes in the chip resistor.

FIG. 9 is a plan view showing a modified example of the cover coat according to the present invention.

FIG. 10 is a plan view showing a shape of a cover coat before reaching the present invention.

FIG. 11 is a plan view showing a printing shift between the cover coat and both auxiliary electrodes in FIG. 10;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2, 3 Upper surface side terminal electrode 4 Resistive film 5 Undercoat 6 Middle coat 7 Cover coat 8, 9 Lower side terminal electrode 10, 11 Side surface electrode 12, 13 Auxiliary electrode 14, 15 Metal plating layer 16 Printed circuit board

Claims (2)

[Claims] 1. A resistive film, terminal electrodes for both ends thereof, and a cover coat covering the resistive film are formed on the surface of the chip-type insulating substrate, and auxiliary electrodes are formed on the surfaces of the two terminal electrodes. In the chip type resistor, the one end on the cover coat side of the two auxiliary electrodes,
On the surface of the cover coat, one end of the two auxiliary electrodes are overlapped so as to protrude from the surface of the cover coat, or
A chip-type resistor, wherein both end portions of the cover coat are overlapped under the two auxiliary electrodes so that one end of the cover coat side of the two auxiliary electrodes protrudes from the surface of the cover coat. Construction. 2. The chip type resistor according to claim 1, wherein a width dimension of a portion where the two auxiliary electrodes overlap in the cover coat is smaller than a width dimension of a portion where the two auxiliary electrodes do not overlap. Structure.